The present invention relates to a power control system for data processing apparatuses or the like, and more particularly to a power control system for balancing the output currents and stabilizing the output voltages of a plurality of switching power supply modules.
Power control systems of this kind according to the prior include what is disclosed in the U.S. Pat. No. 4,924,170. Each of the power supply modules disclosed therein comprises converter means for detecting an amperage supplied to each connected load and converting into a preset corresponding voltage; a comparator means for comparing the voltage from the converting means with a predetermined reference voltage; and pulse width changing means for supplying a power switch with a control signal to enlarge the pulse width when the comparator means determines the voltage from the converting means to be lower than the reference voltage, and supplying the power switch with a control signal to narrow the pulse width when the comparator means determines the voltage from the converting means to be higher than the reference voltage.
This prior art power supply module, however, involves the following problems.
First, since the output amperages from different loads are not in a perfect equilibrium, usually large currents are supplied to some of the loads all the time, with the result that the loads themselves are heavily burdened and deteriorated in reliability.
Furthermore, even if said means is operated to balance the output currents from the loads, it takes time to control the output currents from the loads because the output impedance of each load is extremely small at an amperage below the rated output current, and the output current from the output voltage from each load after adjustment is unstable.